Extrusion die

ABSTRACT

1. An extruding die for extruding an article having a multiplicity of ducts through its length, comprising a plurality of spiders, a plurality of pins extending from each of said spiders, one spider having a central duct and an off-center duct so that the material to be extruded can pass through both ducts.

United States Patent Bustamante et al.

[ Dec. 11, 1973 EXTRUSION DIE Inventors: Santiago J. Bustamante; DonaldH.

Schell, both of Los Alamos, N. Mex.

Assignee: The United States of America as represented by the UnitedStates Atomic Energy Commission, Washington, D.C.

Filed: Oct. 31, 1963 Appl. No.: 320,587

US. Cl. 425/467 Int. Cl. B29c 17/00 Field of Search 207/2, 4, 10.4, 17,

[56] References Cited UNITED STATES PATENTS 326,865 9/1855 Hammill 25/17D 738,665 12/1929 Ober .l 25/17 D Primary Examiner-Robert F. StalilAttorney-John H. Horan EXEMPLARY CLAIM 1. An extruding die for extrudingan article having a multiplicity of ducts through its length, comprisinga plurality of spiders, a plurality of pins extending from each of saidspiders, one spider having a central duct and an off-center duct so thatthe material to be extruded can pass through both ducts.

5 Claims, 3 Drawing Figures PATENIED DEC! 1 I975 Q SHEET 1 BF 2INVENTOR. Santiago J Busfamanfe y Donald H. Schel/ PAIENTEUHEBI 1191a I3.718.217

SNEU 2 0F 2 INVENTOR. Santiago J Bus/amanfe BY Donald H. Sofie/l Fig. 3a

EXTRUSION DIE This invention relates to an extrusion die and, moreparticularly, to a die wherein the extruded article has a multiplicityof holes throughout its length.

It has been known that extrusion dies are capable of extruding tubularshapes. However, increased difficulty is encountered when producing anarticle having a multiplicity of holes throughout its length Such ashape is useful, for instance, in fuel elements for nuclear reactors. Insuch application a large number of holes may be desirable in order toobtain efficient cooling of the fuel element.

The present invention is an extrusion die which permits the extrusion ofarticles having a large number of ducts running throughout its length.One of the principal advantages in the use of this die is the resultingeven density incross-section. The holes are formed by pins dependingfrom dual spiders. As will be seen below, the use of dual spiders insupporting the pins enables the die to extrude an article which is ofconstant crosssectional density.

It is an object of this invention to provide an improved extruding diewhich will extrude an article having a multiplicity of holes throughoutits length.

It is a further object of this invention to provide a die from which canbe extruded an article having a multiplicity of holes, said articlebeing of nearly constant cross-sectional density.

It is anothe object of this invention to provide an extruding die forextruding an article with a multiplicity of holes, said extruding diebeing easily assembled or disassembled and relatively simple tomanufacture.

These and other objects which will hereinafter appear are accomplishedby this invention which is fully described in the specification andshown in the accompanying drawings in which:

FIG. 1 is a cross-section of an extruding die embodying the invention;

FIG. 2 is a section on the line A--A of FIG. 1; and

FIG. 3 is a section on the line BB of FIG. 1.

For purposes of illustration, the embodiment shown in the drawings willproduce an extruded article having 19 ducts throughout its length. Theembodiment comprises a die body 1 which is cylindrical and recessed inorder to contain spiders 2 and 3.

Pins 4 depend from spiders 2 and 3 and provide the mandrels in formingthe multiplicity of ducts 5 in ex truded article 6. It will be notedthat the pins extending from spider 2 pass through a central duct 7 inspider 3. In the embodiment shown, seven pins extend from the centralportions 8 of spider 2. This central portion is suspended from the mainbody of spider 2 by arms 9. The spaces between the main body, centralportion 8 and arms 9 are provided so that the material to be extrudedmay pass through this spider. The seven pins of spider 2 are arranged asone central pin with six others surrounding it. The central pin isscrewed into nut 10. The surrounding pins are force fit into ductsprovided in the spider. The remaining 12 pins are force fit into spider3 in the shape of a hexagon, three pins to a side.

Die body 1 contains three equi-spaced dismantling holes 11. Whendismantling, a plunger rod,not shown, is inserted through thedismantling holes thereby forcing spiders 2 and 3 and their associatedpins out the other side of the extrusion die. Spiders 2 and 3 arenormally held in place by spacer guide 12. Plenum body 13 is tubularwith the inside surface shaped so as to give the desired outside surfaceshape of the extruded article (in the illustrated embodiment, ahexagon). Vacuum ring 14 and its associated O-rings are provided so thata vacuum may be pulled in the extrusion chamber (not shown). Such avacuum is often desirable in order to outgas the material to beextruded.

It can now be seen that the material to be extruded flows from theextrusion chamber (not shown) and is guided by spacer guide 12 and conepiece 15 into the ducts in spider 2 formed by the main body, arms 9 andcentral portion 8. The material to be extruded then follows two pathsthrough spider 3. One of these paths is central (through duct 7) and theother is off-center (through feed holes 16). Since the material flowsboth centrally and off-center through spider 3, the extruded article isof nearly constant cross-sectional density.

While only a single embodiment of the invention has been shown, it is tobe understood that it is capable of many modifications. For example, thenumber of pins may be easily modified. If 37 pins were desired, it isonly necessary that 18 pins be added around the 12 pins of spider 3. Inaddition, it is clear that the spiders 2 and 3 may be composed of aplurality of pieces (e.g., central cylinders and outer rings for ease indismantling). However, this latter modification is disadvantageous inthat it is much more difficult to align the pins so that they are allparallel to each other. Changes, therefore, may be made which do notdepart from the spirit and scope of the invention as disclosed in theappended claims.

What is claimed is:

1. An extruding die for extruding an article having a multiplicity ofducts through its length, comprising a plurality of spiders, a pluralityof pins extending from each of said spiders, one spider having a centralduct and an off-center duct so that the material to be extruded can passthrough both ducts.

2. An extruding die as in claim 1 wherein the pins extending from afirst spider means pass through the central duct in a second spidermeans.

3. An extruding die for extruding an article having a multiplicity ofducts throughout its length, comprising first spider means, secondspider means in tandem with said first spider means, said second spidermeans being positioned closest to the discharge end of the die, aplurality of pins extending from each of said spiders and said secondspider means having a central duct and an off-center duct.

4. An extruding die as in claim 3 wherein the pins extending from thefirst spider means pass through the central duct in the second spidermeans.

5. An extruding die as in claim 3 wherein said second spider means arerecessed from the discharge end of the die.

1. An extruding die for extruding an article having a multiplicity ofducts through its length, comprising a plurality of spiders, a pluralityof pins extending from each of said spiders, one spider having a centralduct and an off-center duct so that the material to be extruded can passthrough both ducts.
 2. An extruding die as in claim 1 wherein the pinsextending from a first spider means pass through the central duct in asecond spider means.
 3. An extruding die for extruding an article havinga multiplicity of ducts throughout its length, comprising first spidermeans, second spider means in tandem with said first spider means, saidsecond spider means being positioned closest to the discharge end of thedie, a plurality of pins extending from each of said spiders and saidsecond spider means having a central duct and an off-center duct.
 4. Anextruding die as in claim 3 wherein the pins extending from the firstspider means pass through the central duct in the second spider means.5. An extruding die as in claim 3 wherein said second spider means arerecessed from the discharge end of the die.